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Abstract: A 71-year-old woman was operated on for undifferentiated lung adenocarcinoma. Four months after surgery, she developed bone and adrenal metastases. She underwent palliative radiation therapy of left scapula and right iliac bone. Thereafter, she started immune checkpoint inhibitor (ICI) therapy with anti-PD-1 antibodies achieving complete tumor response. Twenty months later, a follow-up 18F-FDG PET/CT confirmed tumor response and revealed high radiotracer accumulation in correspondence of retroperitoneal and subcutaneous fat opacities. The contiguous fasciae were mildly thickened. The temporal relation with ICI therapy together with tumor response and corticosteroids therapy effectiveness led to conclude for ICI-related adverse events., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

A 72-year-old man was referred for a triphasic bone scintigraphy to evaluate painful prosthetic implant of the knee. In all the study phases, images showed abnormal uptake close to the tibial portion of the implant. Interestingly, later whole-body images revealed high radiopharmaceutical accumulation in the left hypochondrium. Subsequent radiolabeled leukocyte scintigraphy confirmed radiotracer accumulation in the same localizations. As an important background the patient underwent splenectomy owing to Banti syndrome 60 years earlier. A Tc-labeled heat-damaged red blood cell scintigraphy was then performed, which confirmed radiopharmaceutical accumulation in the left hypochondrium being consistent with splenosis.

A 45-year-old female patient was referred for peptide receptor radionuclide therapy of liver metastases of neuroendocrine origin; the patient had undergone 2 years earlier surgical resection of a grade 2 neuroendocrine neoplasm of ampulla of Vater infiltrating the duodenal submucosa and muscular layers and the neighboring pancreatic tissue. Post-therapy whole-body scan performed to evaluate in vivo radiopharmaceutical distribution confirmed high accumulation in liver lesions and revealed increased uptake in the hip bone. Bone scan and corresponding CT images demonstrated changes of Paget disease in the same district.

We present a 75-year-old-man affected by chronic renal failure in whom metastases from differentiated thyroid cancer (DTC) were incidentally discovered at TcO4 neck-thorax scan in the setting of a diagnosis of secondary hyperparathyroidism. Ten years before, he had undergone near-total thyroidectomy for a multinodular goiter. Result of the pathological examination was negative for DTC. At our observation, serum thyroglobulin was high in the absence of Tg-Ab, consistent with metastatic disease. Neck ultrasonographynography was negative. The patient underwent I therapy (3700 MBq) after stimulation with recombinant human thyroid-stimulating hormone. Postdose whole-body scan confirmed the metastases already demonstrated by TcO4.

It is known that different affinity profiles for somatostatin receptor subtypes among different radiopharmaceuticals result in different organ and tumor uptakes and even in different sensitivities in the detection of lesions. Such differences are considered main factors explaining cases of detecting additional lesions in posttherapy scans with respect to diagnostic imaging. We show a posttherapy scan revealing more lesions--namely, a diffuse bone involvement with many small focal bony uptake areas--than the diagnostic scan using the same radiopharmaceutical (111In-pentetreotide) in a 71-year-old man with metastases from a well-differentiated ileal neuroendocrine tumor.